A series of hydrogen bonding supramolecular liquid crystals consisting of 4-n-alkoxybenzoic acid or 4-n-perfluorohexylbenzoic acid and pyridine derivatives 3a and 3b were reported. Their structures were investigated with nuclear magnetic resonance and infrared spectroscopy and their thermotropic properties were studied with polarized optical microscopy and differential scanning calorimetry. The results showed that no liquid crystalline properties were found for 3a and 3b. Complexes of 4-n-alkoxybenzoic acid with 3a and 3b displayed nematic phase and smectic C phase, while complexes of 4-perfluorohexylbenzoic acid with 3a and 3b exhibited multiple smectic phases. 4a-n had both higher melting and clear points than 4b-n, while 4b-n exhibited odd-even effect. The infrared spectra demonstrated the hydrogen bonds existed between the benzoic acid and pyridine moieties in the supramolecular systems.

Key words: hydrogen bond, liquid crystal, supramolecular chemistry, fluorophobic effect, perfluorohexylbenzoic acid, pyridine derivative